{
	package STATE;
	use strict;
	use warnings;
	use Storable qw( retrieve store );
	use constant FILENAME => sprintf '%s.state', $0;
	sub import {
		no strict 'refs';
		my $p = caller;
		*{"$p\::STATE"} = (${^STATE}{$p}||={});
	}
	sub BEGIN {
		%{^STATE} = %{ -f FILENAME ? retrieve FILENAME : {} }
	}
	sub END {
		store \%{^STATE} => FILENAME;
	}
}
1;